Enzymic determination of branched-chain amino acids and 2-oxoacids in rat tissues. Transfer of 2-oxoacids from skeletal muscle to liver in vivo.
1. A procedure is described for the purification of leucine dehydrogenase (EC 1.4.1.9) from Bacillus subtilis. 2. The preparation is suitable for the quantitative assay of branched-chain amino acids and their 2-oxoacid analogues. 3. The content of total branched-chain 2-oxoacids in freeze-clamped liver, kidney, heart or mammary gland of fed rats is less than 5 nmol/g fresh wt. Higher amounts are present in skeletal muscle and arterial blood (25 +/- 4 nmol per g fresh wt., and 33 +/- 6 nmol per ml respectively; means +/- S.D. of 3 and 11 animals respectively). The values are not significantly affected by starvation for 24 h. 4. Arteriovenous difference measurements show that considerable amounts of branched-chain 2-oxoacids are released by skeletal muscle into the circulation and similar amounts are removed by the liver (about 1 mmol/24 h in a 400 g rat).
D000594:Amino Acid Oxidoreductases / Q000302:isolation & purification; D000597:Amino Acids, Branched-Chain / Q000032:analysis* / Q000378:metabolism; D000818:Animals; D001412:Bacillus subtilis / Q000201:enzymology; D005260:Female; D007651:Keto Acids / Q000032:analysis* / Q000378:metabolism; D007700:Kinetics; D007930:Leucine / Q000302:isolation & purification; D050803:Leucine Dehydrogenase; D008099:Liver / Q000378:metabolism*; D008297:Male; D008722:Methods; D009132:Muscles / Q000378:metabolism*; D051381:Rats; D014018:Tissue Distribution
D000597:Amino Acids, Branched-Chain; D007651:Keto Acids; D000594:Amino Acid Oxidoreductases; D050803:Leucine Dehydrogenase; D007930:Leucine